Process for separating mineral oil products



Patented Feb. 8, 1938 PATENT OFFICE PROCESS FOR SEPABATING OIL PRODUCTS Hermann Suida and Hans P611, Vienna, and Alfred Nowak, Modling, Austria No Drawing. Application April :4, i935, set-a1 No. 18,014. in Austria May 5. 1m

10 Claims. (01. 190-13) The present specification relates to aprocess for separating mineral oil products, distillates or concentrates into paraiiinic, naphthenic and aromatic portions with simultaneous refining of the 5 parafllnic and naphthenic portions.

In the solvent processes hitherto known for extracting and refining mineral oil products there occurs only a separation into a refined paraflinic portion which is more or less pure and into anextract which contains all the aromatic, resinous and asphaltic substances, as well as the whole or part of naphthenic substances. In these processes it is either necessary, if the yield of the refined parafiins is to be large, to dispense with particular purity of the parafllns since these are more or less contaminated by naphthenic substances; if however, it is desired to obtain the paraflins in a very pure state and free from naphthenesthe yield will be a very limited one.

By previous investigations we have already discovered that it is possible to separate mineral oil-products, distillates and concentrates into three portions:

Aparafiinic portion of excellent quality,

A valuable cyclic (naphthenic) portion, and

A portion containing aromatic, resinous and asphaltie substances. This separation is carried out by using only one solvent, viz. crude cresol,

on the one hand, in anhydrous state, on the other 'hand, in aqueous state.

We have now discovered, and this is the subject matter of the present invention, that it is possible to obtain much ,better results compared with those which are obtained by working with the above mentioned crude cresol, by using as a solvent a mixture of anhydrous crude cresol with a second liquid of water repellent nature, which has also a greater dissolving power for naphity of the solvent as a whole.

According to the present inventionthis mixonly the aromatic, resinous and asphaltic sub- 50 stances.

The use of a secondsolvent having a great dissolving power for naphthenic oils together with crude cresol effects a decrease of the viscosity in thef extraction process and lowers the total 55 amount of solvent required, without reducing the thenic oils and is capable of lowering the viscos-.

after it is applied saturated with water for the water absorbent capacity of the crude cresolthe amount of the second solvent added to the crude cresol being only small-to an extent which would render impossible the complete separation of the useful naphthen'ic portions.

As a supplemental solvent added to crude-cresol all liquid solvents for naphthenic substances are suitable which are of a highly water repellent nature and do not differ too far in their boiling point from the boiling range of crude cresol. Since the additional solvents, as already mentioned, should lower the viscosity of the cresol and the mixed solvent as a whole they must not tend themselves to associate as strongly as cresol. The before-mentioned features apply for instance to the following solvents:

Nitrobenzene, nitrotoluene, xylidines, ethylaniline, dichiorobenzenes, dichloro-diethyl-ether and others. The above mentioned examples of additional solvents are mentioned to illustrate the invention without restricting its scope.

According to the present invention these solvent mixtures are used for separating mineral oil products, distillates and concentrates into a refined parafilnic portion, a refined naphthenic portion and a portion containing aromatic, resinnus-and asphaltic substances.

In carrying out the process according to the invention we may proceed by allowing the anhydrous mixture of solvents to act on the mineral oil product at about C. below the temperature of demulsification. the paraifinic portion .thus remaining undissolved in a state of high purity. Thereafter the naphthenic portions are separated in a pure state by saturating the extract with water. The process may also be carried out in such a manner, that at an increased temperature the entire mineral oil products are dissolved in the anhydrous solvent into a clear solution, whereafter the solution is cooled down to about 15 C. below the temperature of demulsification in order to separate the parafiinic portion.

to carry out the above described method of separation only after having subjected the mineral oil product to a preliminary purification by extracting, with a certain quantity of the aqueous mixture of solvents, the main portion of the asphaltenes, resins and aromatic substances. After this preliminary extraction has been carried out the main treatment is performed in'the manner as described before, that is to say the solvent is first applied in the anhydrous state so that the parafllnic portion remains undissolved in a pure In some cases it has proved to be advantageous I 2 state, whereafter by saturating with water the naphthenes are separated from the extract. It

a the process is carried out in this manner two aqueous extracts are obtained which are joined afterwards. Although in this way a larger quantity of solvent is consumed this modification in some cases enables the naphthenic portion to be obtained in a purer state than. by the normal method, the yield being approximately equal.

The saturation with water of the extract containing the naphthenic and aromatic portions, which is a feature of the present process, is not similar to the addition of wateraccording to the known methods which use'the water for recoveringthe solvent from mixtures of oil and solvent. For in these latter processes the water does not brin about a separation between naphthenic and aromatic oils, that is a separation 01' two portions of the oil to be refined, but in the known processes the water only serves for separating and recovering the solvent from the hydrocarbon with which it is in a homogeneous liquid phase.

The process is very flexible as regards the quality of the material to be treated as well as the quantity and quality of the paraifinic and naphthenic portions. Contrary to the processes used up to the present the maximum quantity of solvent required is small.- With very dark distillates the maximum quantity of solvent amounts to .150 per cent. of the distillate. When treating materials of higher purity the required quantity can sometimes be reduced to about 100 per cent. The extraction with an anhydrous mixture of solvents ,may be carried out periodicallyor continuously;

In the periodical mode of execution the total amount of solvent is divided into three unequal portions, and the extraction is first carried out with the largest portion, then with the smaller portion and finally with the smallest portion. In all of these three cases the oil may be brought completely into solution by heating it andthen the separation takes place by cooling.

The process maybe performed in three centriiugal saparators arranged in series, each of which is connected to a mixing apparatus. In this case the work may be carried out continuously in counter-current... It extraction towers are used it is also possible to operate continuously in counter-current. The saturation of the extract with water and the precipitation of the naphthenic portion may preferably be carried out by amixing pump, whereafter the separation takes place in a settling tank or in a centrifugal separator.

If smaller quantities oi solvent are used the yield of parafiinic portions oi. highest purity is not increased but the yield of naphthenic substances becomes larger. It may be advantageous! to use a smaller 7 amount of solvent it the oil to be treated is sufiiciently pure to give naphthenes of satisfactory purity though they are separated in a larger quantity in consequence of the small amount of solvent used. I

An increase in the yield of the parafiinic por-" tions-though of a somewhat inferior quality'1s brought-about by working at a lower temperature when separating the. anhydrous extract from the parafiinic'portions. By this mode of operation purely naphthenic bodies will be separated together with the parafiinic ones and increase the yield of the latter. 7

In some cases it may be desirable to choose this working method particularly ii the naph- I 8.3 Engler at 50' low' specific gravity tion the process may be adapted to any requirements.

The separated parafiinic and naphthenic raffinates contain a few percent of solvent which are recovered by distilling ofi in vacuum until there remains only a small amount which is removed by blowing with some superheated steam. If necessary, the rafiiuates free from solvent are mixed with 1 per cent. of bleaching earth, filtered and are then, ready 'for use without further treatment. 4

I! a further improvement of the naphthenic portion isdesired the latter may be treated again with a certain quantity of anhydrous solvent at low temperature; by this means it is possible to obtain, even in the most unfavourable cases, naphthenic rafiinates with light colour and good resistance against oxidation. In most cases such after-treatment is, however, not necessary.

The paraiiinic and naphthenic rafiinates-obtained according to the present process all show, apart from their excellent viscosity properties (highest possible viscosity index) and from the low specific gra ity, exceedingly good resistance against oxidation.

The process is illustrated by amples:

Example 1.-100 parts of a crude distillate of a mixed baseEuropean oil (Vw=9,9 Engler, viscosity index (according to Walther) mVk= 4.21) are agitated with 150 parts of a mixture of parts of crude cresoland 15 parts of nitrobenzene. The separated parafilnic portion is completely refined, light yellow and has a viscosity index (Walther) of mVk=3.78. 27 parts of this railinate are obtained.

' Theextract is saturated with water, allowed the following exto settle, whereafter the top layer which has a bright blue fluorescence is removed. It consists of pure naphthenic components, is completely free from resins and thus refined and has a viscosity index (Walther) of 4.02. The yield is 41 parts. The remaining extract containing the mixture of solvents is completely separated by distillation, if desired with steam, from the solvent mixture and consists of a dark oil which contains the aromatic, resinous and asphaltic substances.

If nitrobenzene alone is used for separating the parafiinic portions, only 23 parts of paraflinic components having the same viscosity index are obtained. If crude cresol is alone used 31 parts of a parafflnic oil having a. somewhat inferior viscosity index are obtained but. only 38 parts of naphthenic oils. For this separation 150 parts of solvent are notrsuflicient, but his necessary to use 200-250 parts of crude cresol.

Example 2. distillate, specific gravity 0.922 at 20 C., viscosity C., viscosity index (A. S. T. M.) 50 is treated at a temperature of 10 (2., with parts of a mixture or 85 per cent. by volume of crude cresol and 15 parts by volume of nitrotoluene in a unit consisting of three mixing pumps and three centrifugal separators arranged in series. In the first mixing pump, the oil-is intimately mixed with 80 parts of solvent and in the first separator the extract is separated from the undissolved oil; thereupon the undissolved oil is mixed in the second mixing pump with 40 parts of fresh solvent and the undissolved oil separated in the second separator. The process is repeated in the third mixing pump and in the third separaparts of a Russian engine oil tor with ,20 parts of fresh solvent.- The extracts from the three separators are joined. The oil which has remained undissolved is freed as in Example 1 from remainders of solvent and consists of a very light parafilnic rafiinate having a specific gravity of 0.885 at 20 C., a viscosity of 55 Engler at 50 C. and a viscosity index of 90. The yield is 52 per cent. by volume of the distillate. The joined extracts are intimately mixed in a fourth mixing pump with 10 parts of water and from a fourth separator the naphthenic oil is discharged in a clear state. It is then freed from solvent rema nders as described in Example 1,

. mixed while warm with 1 per cent. of bleaching earth, filtered and consists then of a rafiinate having a good colour, a'specific gravity of 0.910 at 20 C., a viscosity of 'I.8 Engler at 50 C. and a viscosity index of 72. The yield amounts to 28 per cent. by volume of the distillate. The extract saturated with water is mixed with 40 percent.

of a medium gasoline and the water is completely.

removed by distilling off the gasoline. The anhydrous extract is now freed i'rom solvent by distillation in vacuum, the solvent being obtained in an anhydrous state.

. Example 3.-100 parts of a Russian Brightstock.

specific gravity 0.905 at 20 C., viscosity 31 Engler at 50 C., viscosity index 84, are extracted with 120 parts of a mixture of 80 per cent. by volume of crude cresol and 2,0 per cent. by volume of dichloro-diethyl-ether. The mode of operation is as in Example 2, that is to say the solvent is divided into three portions and the extraction is performed at 35 to C. The parafilnic raflinate freed from remainders of solvent has a specific gravity of 0.896 at 20 C., a viscosity of 25.6 Engler at C. and a viscosity index of 93, it is of a light green-yellow colour, completely transparent and obtained in a yield of 74 per cent. by volume of the oil treated. The naphthenic railinate is obtained by separating with water, distilling off and filtering with 1 per cent. of bleaching earth to a bright colour and a yield of 18.5 per cent. The specific'gravity is 0.914 at 20 C., the

and 18 per cent. by volume of dichioro-benzene (liquid), the solvent being divided into several portions. The parafiinic distillate thus obtained shows a light colour, the yield being 30 per cent.

- by volume, specific gravity 0.880 at 20 C.,v visof the naphthenes being dissolved and per cent.

remaining undissolved. After separating the remainders of solvent by distilling in vacuum and blowing with superheated steam, the naphthenic rafiinate twice refined shows a very light colour,'a

specific gravity of 0.900 at 20 C., a viscosity of Engler at 50 C. and a viscosity index of 90.

Example 5. parts of a spindle oil distillate of Asiatic origin, having a specific gravity of 0.895

' and nitrobenzene. i

at 20 C., a viscosity of Engler at 50 C., a viscosity index of 32 are extracted in three portions with 100 parts of a mixture of 80 per cent. by volume of crude cresol and 20 per cent. by

, volume of ortho-toluidene at 10 C. The parafflnic ramnate is obtained very light in colour and with a yield of 40 per. cent. by volume, the specific gravity being 0.850 at 20" 0., the viscosity 1.9o

Engler at 50 C. and, the viscosity index 92. The naphthenic portions separated with water amount to 35 per cent. by volume of the oil treated, have light colour and show a specific gravity of 0.875 at 20 C., a viscosity of 2 Engler at 50 C. and a viscosity index of 60. The oil contained in the extract in a. quantity of 25 per cent. by volume of the oil treated consists of a dark oil, having a specific gravity of 0.975 at 20 C. a viscosity of 3.8" Engler at 50 C. and a viscosity index of 38.

Naphthenic acids which in some oils are present in larger quantities, particularly in Roumanian oils, but also in several other distillates, pass over into the extract when the oils are treated according to the above described methods; thus by the extraction also a complete deacidification of the distillates in question is effected. What we claim is:- v 1. In a process for separating and refining mineral oils containing parafiinic, napththenic and aromatic portio by the alternate use of a' selective solvent in a firhydrous and water saturated stages; the improvement 'which comprises employing as the solvent a mixture consisting solely of crude cres'ol and a waterrepellent selective solventwhich has a high dissolving power for naphthenic oils and is capable of lowering the viscosity of the solvent as a whole.

2. A process for separating mineral oil products into paramnic, naphthenic and aromatic portions with simultaneous refining of theparaffinic and naphthenic portions, which comprises treating the mineral oil product with an anhydrous mixture consisting of crude cresol and a water repellent solvent which has a high dissolving power for naphthenic oils, the paraflinic portion being separated thereby in ,a refined state, thereafter saturating the extract;with water, the naphthenic portion being thereby separated in a refined state, the aromatic, resinous and asphalt compounds remaining in the mixture of solvent and water being finally recovered therefrom.

3. A process for separating mineral oil products into paraflinic, naphthenic and aromatic portions with simultaneous refining of the paraffinic and naphthenic portions which comprises first extracting the oil products with a water sat-' urated mixture consisting of crude cresol and a water repellent solvent, thus dissolving the main quantity of aromatic resinous and asphaltic compounds, thereafter extracting the undissolved portion of the oil with an anhydrous mixture of said solvents, separating the parafllnic portions in a pure state, saturating the extract with water, thereby separating the naphthenic substances in a pure state and finally joining the. solution of aromatic, resinous and asphaltic compounds in the aqueous mixture of solvents with the aqueous extract, first obtained.

' 4. A process as set forth claim 1 wherein the v6. A process as set forth in claim 1, wherein the solvent consists of a mixture of crude cresol 9. A'process as set forth in claim 1, wherein and xylidine. the water repellent solvent is an arylamine.

7. A process as set forth-in claim 1, wherein 10. A process as set forth in claim 1, wherein the solvent consists of a mixture of crude cresol the water repellent solvent is an organic halogen 5 and dichlorbenzene. derivative.-

8. A process as set forth in claim 1, wherein the HERMANN SUIDA. water repellent solvent is a. nitro-aromatic com- HANS P6LL.

pound. I V r ALFRED NOWAK; 

